U.S. patent number 6,486,444 [Application Number 09/505,901] was granted by the patent office on 2002-11-26 for load-lock with external staging area.
This patent grant is currently assigned to Applied Materials, Inc.. Invention is credited to Kelly A. Colborne, Kevin Fairbairn, Howard E. Grunes, Christopher Lane.
United States Patent |
6,486,444 |
Fairbairn , et al. |
November 26, 2002 |
Load-lock with external staging area
Abstract
The present invention generally provides a vacuum system having
a small-volume load-lock chamber for supporting a substrate set of
only two rows of substrates, which provides for quick evacuation
and venting of the load-lock chamber to provide a continuous feed
load-lock chamber. More particularly, the present invention
provides a transfer chamber; one or more processing chambers
connected to the transfer chamber; a substrate handling robot
disposed in the transfer chamber; and at least one load-lock
chamber connected to the transfer chamber, and having one or more
substrate support members for supporting one or more stacks of only
two substrates per stack. Another aspect of the invention provides
a staging, or storage rack associated with or integrated with the
load-lock chamber. More particularly, the staging, or storage rack
may be located outside the transfer chamber and accessible by a
staging robot serving the load-lock chamber. The staging or storage
rack may temporarily store processed substrates for cooling of the
substrates prior to replacing the substrates within substrate
cassettes during idle time of the staging robot. In this way, the
substrates may continue to be cooled without interrupting the
operation of the load-lock chamber.
Inventors: |
Fairbairn; Kevin (Los Gatos,
CA), Grunes; Howard E. (Santa Cruz, CA), Lane;
Christopher (San Jose, CA), Colborne; Kelly A. (San
Jose, CA) |
Assignee: |
Applied Materials, Inc. (Santa
Clara, CA)
|
Family
ID: |
26835146 |
Appl.
No.: |
09/505,901 |
Filed: |
February 17, 2000 |
Current U.S.
Class: |
219/390;
118/50.1; 118/724; 219/405; 392/416; 219/411 |
Current CPC
Class: |
H01L
21/67196 (20130101); H01L 21/67742 (20130101); H01L
21/67745 (20130101); H01L 21/68707 (20130101); H01L
21/67201 (20130101) |
Current International
Class: |
H01L
21/67 (20060101); H01L 21/687 (20060101); H01L
21/677 (20060101); H01L 21/00 (20060101); F27B
005/14 () |
Field of
Search: |
;219/390,405,411
;392/416,418 ;118/724,725,50.1 |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
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6-132379 |
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May 1994 |
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JP |
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6-314730 |
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Nov 1994 |
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JP |
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7-086169 |
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Mar 1995 |
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JP |
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7-094489 |
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Apr 1995 |
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JP |
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7-142552 |
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Jun 1995 |
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JP |
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7-335711 |
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Dec 1995 |
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JP |
|
9-246347 |
|
Sep 1997 |
|
JP |
|
10-275848 |
|
Nov 1998 |
|
JP |
|
Primary Examiner: Walberg; Teresa
Assistant Examiner: Fuqua; Shawntina T
Attorney, Agent or Firm: Moser, Patterson & Sheridan
Parent Case Text
This application claims the benefit of No. 60/137,324, filed Jun.
3, 1999.
Claims
What is claimed is:
1. A vacuum apparatus for processing substrates, comprising: (a) a
transfer chamber; (b) one or more processing chambers connected to
the transfer chamber; (c) a substrate handling robot disposed in
the transfer chamber; and (d) at least one load-lock chamber
connected to the transfer chamber, and having one or more substrate
support members for supporting one or more stacks of two
substrates; and (e) one or more storage racks associated with the
load-lock chamber for receiving and temporarily storing substrates
externally to the load-lock chamber.
2. The apparatus of claim 1, wherein the racks further comprise a
substrate staging area.
3. The apparatus of claim 2, further comprising a staging robot
disposed in the staging area to load substrates into and remove
substrates from the load-lock chamber.
4. The apparatus of claim 3, wherein the staging robot is
positioned between a first and a second substrate cassette
turntable.
5. The apparatus of claim 4, wherein the substrate handling robot
comprises a plurality of substrate handling blades for concurrently
transporting a plurality of substrates between the load-lock
chamber and the one or more processing chambers.
6. The apparatus of claim 5, wherein the plurality of substrate
handling blades are coplanar.
7. The apparatus of claim 6, wherein the one or more storage racks
are for receiving and temporarily storing substrates between
transfer of a substrate between the load-look chamber and substrate
storage cassette.
8. The apparatus of claim 7, wherein at least one of the one or
more storage racks is adapted to temporarily receive and cool
processed substrates retrieved from the load lock chamber following
processing in the one or more processing chambers.
9. The apparatus of claim 8, wherein at least one of the one or
more storage racks is adapted to temporarily receive and cool
processed substrates includes a cooling element.
10. The apparatus of claim 7, wherein at least one of the one or
more storage racks is adapted to temporarily receive and pre-heat
unprocessed substrates retrieved from a substrate cassette for
processing in the one or more processing chambers.
11. The apparatus of claim 10, wherein at least one of the one or
more storage racks is adapted to temporarily receive and pre-heat
unprocessed substrates includes a heating element.
12. The apparatus of claim 7, wherein the load-lock chamber
includes a heating element disposed in connection therewith for
pre-heating unprocessed substrates in the load-lock chamber.
13. The apparatus of claim 1, wherein each of the at least one
load-lock chambers includes a single substrate support member for
receiving a single stack of two substrates.
14. The apparatus of claim 1, wherein each of the at least one
load-lock chambers includes a dual substrate support member for
receiving two stacks of two substrates each.
15. The apparatus of claim 1, having a plurality of load-lock
chambers, each load-lock chamber connected to a different facet of
the transfer chamber.
16. The apparatus of claim 13, wherein the at least one load-lock
chambers is a single load-lock chamber connected to a single facet
of the transfer chamber.
17. A method of processing substrates, comprising: (a) providing
unprocessed substrates to a load-lock chamber with a staging robot;
(b) retrieving the unprocessed substrates from the load-lock
chamber with a substrate handling robot located within a transfer
chamber; (c) processing the unprocessed substrates in one or more
process chambers connected to the transfer chamber; (d) returning
the processed substrates in the load-lock chamber with the
substrate handling robot; (e) retrieving the processed substrates
from the load-lock chamber with the staging robot; (f) placing the
processed substrates in a cooling station located external to the
load-lock chamber and the transfer chamber; (g) allowing the
processed substrates to cool in the cooling station; and (h)
retrieving the processed and cooled substrates from the cooling
station with the staging robot and placing them in substrate
cassettes.
18. A method of processing substrates, comprising: (a) providing a
vacuum apparatus with a transfer chamber, one or more processing
chambers connected to the transfer chamber, a substrate handling
robot disposed in the transfer chamber, and a single load-lock
chamber connected to the transfer chamber and having at least one
substrate support member for supporting two substrate sets; (b)
initially loading the load-lock chamber and transfer chamber with
unprocessed substrates; (c) processing a substrate in one or more
processing chambers; (d) removing the processed substrate from the
one or more processing chambers with a substrate handling robot;
(e) placing the processed substrate within the load-lock chamber
with the substrate handling robot; (f) retrieving the unprocessed
substrate within the load-lock chamber with the substrate handling
robot; (g) retrieving the processed substrate within the load-lock
chamber with a staging robot located external to the load-lock
chamber; (h) placing the processed substrate within a storage rack
located external to the load-lock chamber with the staging robot;
and (i) repeating steps c through h, while retrieving cooled
substrates from the storage rack with the staging robot and placing
the cooled substrates within substrate cassettes with the staging
robot during staging robot idle time.
19. The method of claim 18, wherein each substrate set includes a
single substrate in each of two substrate stacks.
20. The method of claim 19, including the step of pre-heating the
unprocessed set of substrates within the load-lock chamber prior to
its removal by the substrate handling member.
21. The method of claim 19, including the step of pre-heating the
unprocessed set of substrates within the storage rack prior to its
placement in the load-lock chamber.
22. The method of claim 18, wherein each substrate set includes a
single substrate in a single substrate stack.
23. The method of claim 22, including the step of pre-heating the
unprocessed set of substrates within the load-lock chamber prior to
its removal by the substrate handling member.
24. The method of claim 22, including the step of pre-heating the
unprocessed set of substrates within the storage rack prior to its
placement in the load-lock chamber.
25. A staging module for use with a substrate processing system,
comprising: (a) at least one load-lock chamber adapted to be
connected to a transfer chamber of the substrate processing system;
and (b) one or more storage racks associated with the load-lock
chamber for receiving and temporarily storing substrates.
26. The staging module of claim 25, wherein at least one of the one
or more storage racks is a cooling rack adapted to cool processed
substrates following processing by the substrate processing
system.
27. The staging module of claim 25, wherein at least one of the one
or more storage racks is a pre-heating rack adapted to pre-heat
unprocessed substrates prior to processing by the substrate
processing system.
28. The staging module of claim 26, wherein the cooling rack
includes a cooling element.
29. The staging module of claim 27, wherein the pre-heating rack
includes a pre-heating element.
30. The staging module of claim 29, wherein the pre-heating rack
includes a substantially thermally transparent window between the
heating element and the substrate.
31. The staging module of claim 30, wherein the substantially
thermally transparent window is a quartz window.
32. A method for processing substrates, comprising: transferring a
substrate to a rack disposed in atmospheric staging area of a
factory interface that is coupled to a load-lock chamber; and
thermally conditioning the substrate in the staging area.
33. The method of claim 32, wherein the step of transferring
further comprises: transferring the substrate from the load-lock
chamber to the staging area.
34. The method of claim 32, wherein the step of transferring
further comprises: transferring the substrate from a substrate
storage cassette to the staging area.
35. The method of claim 32, wherein the step of thermally
conditioning the substrate further comprises heating the substrate;
and transferring the substrate to the load-lock chamber.
36. The method of claim 32, wherein the step of thermally
conditioning the substrate further comprises cooling the substrate;
and transferring the substrate to a substrate storage cassette.
37. A vacuum apparatus for processing substrates, comprising: (a) a
housing adapted to receive one or more substrate storage cassettes;
(b) one or more substrate storage racks disposed in the housing
each rack having a cooling element; (c) a port formed in the
housing and adapted be coupled to a load-lock chamber; and (d) a
robot disposed in the housing and adapted to transfer substrates
between the racks, substrate storage cassettes and the load-lock
chamber.
38. A vacuum apparatus for processing substrates, comprising: (a) a
transfer chamber; (b) one or more chambers connected to the
transfer chamber, wherein at least one of the one or more chambers
are selected from the group consisting of a processing chamber and
a load lock chamber having one or more substrate support members
for supporting one or more stacks of two substrates; (c) a
substrate handling robot disposed in the transfer chamber; and (d)
one or more storage racks including a thermal control element,
wherein the one or more storage racks are external to the transfer
chamber and the one or more chambers connected to the transfer
chamber.
Description
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates generally to the storage and transfer
of substrates typically used in the fabrication of electronic
devices such as integrated circuits and flat panel displays.
Specifically, the invention relates to a load-lock chamber and a
pre-processing or post-processing storage rack used to transition
substrates from one environment to another environment in a
processing system.
2. Background of the Invention
Vacuum processing systems used in the fabrication of integrated
circuits and flat panel displays are generally known. An example of
a vacuum processing system 100 is shown in FIGS. 1 and 2. The
vacuum processing system 100 typically has a centralized transfer
chamber 102 mounted on a monolith platform or main frame structure
110. One or more process chambers 106 are in communication with the
transfer chamber 102 via access ports 105 and associated slit
valves 107. Substrates are passed through the system by a substrate
handling robot 103 disposed in the transfer chamber 102. The slit
valves 107 isolate the process chambers 106 from each other and
from the transfer chamber 102 while substrates are being processed.
The transfer chamber 102 is typically held at a constant vacuum,
while the process chambers 106 may be pumped to a greater or lesser
vacuum than the transfer chamber 102 for performance of their
respective processes. Afterward, the process chamber pressure
returns to the level in the transfer chamber 102 before opening the
slit valve 107 is opened to permit access between the chambers.
The substrate handling robot 103 disposed in transfer chamber 102
typically retrieves one or more unprocessed substrates from one or
more load-lock chambers 112 connected to the transfer chamber 102
and places the substrates in the process chambers 106. The
load-lock chambers 112 selectively cycle between the pressure level
of the ambient environment and the pressure level in the transfer
chamber 102 to transition the substrates between atmospheric
pressure and the vacuum environment of the transfer chamber 102.
The load-lock chambers 112 typically have a large volume and store
multiple substrates. Typically, twelve to twenty-four substrates
are stacked vertically in one or more substrate cassettes 109
disposed in load-lock chambers 112. The substrate cassettes 109
typically include a plurality of substrate supports spaced
vertically to permit a substrate handling robot blade 115 to reach
under a substrate to remove or place a substrate. Substrates are
typically loaded in and removed from the load-lock chamber 112 by
either a staging robot 113 (shown in FIGS. 1 and 3), or an operator
at or near a frontend staging area 104.
Typically, the front-end staging area 104 is maintained at or near
ambient or atmospheric pressure. Accordingly, prior to transfer of
substrates into or out of the loadlock chamber 112, the atmospheric
volume within the load-lock chamber 112 must be vented to
atmospheric pressure before opening the valves of the load-lock
chamber 112. Similarly, before transfer of substrates between the
load-lock chamber 112 and the transfer chamber 102, the atmospheric
volume within the load-lock chamber 112 must be evacuated to the
low pressure maintained in the transfer chamber 102. Because of the
sizable volume within typical load-lock chambers 112, a relatively
lengthy amount of time is required to vent and then evacuate the
load-lock chamber 112 before permitting access to the substrates by
the substrate handling robot 103 This process may typically take
approximately four (4) minutes to complete. During this time, the
vacuum processing system 100 typically sits idle while awaiting the
introduction of additional unprocessed substrates into the
system.
It has been found that substantial production gains can be made by
reducing the atmospheric volume within the load-lock chamber 112
serving the transfer chamber 102. Accordingly, systems having
single substrate load-lock chambers have been developed to reduce
venting and evacuation time within the load-lock process chamber
112, which has resulted in a reduction of process chamber idle time
and an increase in production. One exemplary system of this type is
shown in U.S. patent application Ser. No. 08/990,396, entitled
"Single Wafer Load-lock Chamber For Pre-Processing And
Post-Processing Wafers In A Vacuum Processing System," filed on
Feb. 15, 1997, which is incorporated herein by reference.
However, the reduction in the number of substrates housed in the
load-lock chamber 112 requires that the substrates must be
transferred quickly into and out of the load-lock chamber 112. This
can be problematic when substrates must be pre-heated prior to
processing or cooled following processing before being replaced
into a substrate cassette 109. Unfortunately, a shorter transition
time through the load-lock chamber 112 may prevent the load-lock
chamber 112 from sufficiently pre-heating a substrate prior to
processing or cooling a substrate following processing.
To accommodate this cooling and/or pre-heating process, existing
systems have provided cooling and/or pre-heating chambers attached
to the transfer chamber 102. Because space may be limited on a
typical transfer chamber 102, such systems are required to forfeit
a facet on which a processing chamber 106 could be mounted.
Alternatively, systems may have limited throughput due to a limited
number of preheating/cooling chambers mounted to the transfer
chamber 102 and/or the amount of time required to perform the
pre-processing/post processing procedures. In systems where heating
and/or cooling members are integrated within the load-lock chamber
112, throughput may be limited because a cooling process may
require an extended cooling time beyond the time in which the
substrate handling robot 103 can return to the load-lock chamber
112 to return a processed substrate or retrieve an unprocessed
substrate for further processing. As a result, the system substrate
transfer system is limited by the time required for the cooling
process to be performed.
Accordingly, there is a need for a vacuum processing system that
provides high throughput and pre-processing and/or post-processing
processes. More particularly, there is a need for an integrated
system having a load-lock chamber with an integrated staging, or
storage rack mounted external to the transfer chamber for
pre-processing and/or post-processing of substrates.
SUMMARY OF THE INVENTION
The present invention generally provides a vacuum apparatus for
processing substrates, comprising a transfer chamber; one or more
processing chambers in communication with the transfer chamber; a
substrate handling robot disposed in the transfer chamber; and at
least one load-lock chamber connected to the transfer chamber, with
the load-lock chamber having one or more substrate support members
for supporting one or more substrates. The apparatus preferably
includes a substrate staging area and may further include a staging
robot disposed in the staging area to load substrates into and
remove substrates from the load-lock chamber.
In another aspect of the invention, the staging area may include
one or more storage racks associated with the load-lock chamber for
receiving and temporarily storing substrates. Further, the storage
racks, preferably include at least a cooling element and are
adapted to temporarily receive and cool substrates retrieved from
the load-lock chamber following processing.
In another aspect of the invention, at least one of the storage
racks may include a heating element adapted to pre-heat unprocessed
substrates retrieved from the substrate cassette prior to
processing. Further, the storage racks may include a cooling
element and/or a heating element, each adapted to receive and
process a substrate prior to transfer. Still further, the load-lock
chamber may include a heating element disposed in connection
therewith for pre-heating unprocessed substrates in the load-lock
chamber, and the load-lock chamber may include a substrate support
member for receiving a substrate thereon.
In another aspect of the invention, the load-lock chamber may
include a substrate support member for receiving a single stack of
two or more substrates thereon, preferably in a single load-lock
chamber connected to a single facet of the transfer chamber.
Further, each load-lock chamber may include a dual substrate
support member for receiving two stacks of two substrates thereon.
In another aspect, a plurality of load-lock chambers may be
provided, wherein each load-lock chamber is connected to a
different facet of the transfer chamber.
In another aspect, the invention is directed to a method of
processing substrates, comprising the steps of providing
unprocessed substrates to a load-lock chamber with a staging robot,
retrieving the unprocessed substrates from the load-lock chamber
with a substrate handling robot located within a transfer chamber,
processing the unprocessed substrates in one or more process
chambers connected to the transfer chamber, returning the processed
substrates to the load-lock chamber with the substrate handling
robot, retrieving the processed substrates from the load-lock
chamber with the staging robot, placing the processed substrates in
a cooling station located external to the load-lock chamber and the
transfer chamber, and cooling the substrate in the cooling station;
and retrieving the cooled substrates from the cooling station with
the staging robot and placing them in a substrate cassette.
In another aspect, the invention is directed to a method of
processing substrates, comprising: a) providing a vacuum apparatus
with a transfer chamber, one or more processing chambers connected
to the transfer chamber, a substrate handling robot disposed in the
transfer chamber, and a load-lock chamber connected to the transfer
chamber and having at least one substrate support member for
supporting a substrate thereon; b) initially loading the load-lock
chamber and transfer chamber with one or more unprocessed
substrates; c) processing the substrates in one or more processing
chambers; d) removing the processed substrates from the one or more
processing chambers with a substrate handling robot; e) placing the
processed substrates within the load-lock chamber with the
substrate handling robot; f) retrieving the processed substrates
within the load-lock chamber with a staging robot located external
to the load-lock chamber; g) placing the processed substrates
within a storage rack located external to the load-lock chamber
with the staging robot; and h) repeating steps c) through g), while
retrieving cooled substrates from the staging or storage rack with
the staging robot and placing the cooled substrates within
substrate cassettes with the staging robot during staging robot
idle time.
Further, each substrate set may include a single substrate in each
of two substrate stacks, and the method may further include the
step of pre-heating the unprocessed set of substrates within the
load-lock chamber prior to removal by the substrate handling
member. Further, the method may include the step of pre-heating the
unprocessed set of substrates within the storage rack prior to
their placement in the load-lock chamber.
In still another aspect, the invention is directed to a staging
module for use with a substrate processing system, comprising: at
least one load-lock chamber adapted to be connected to a transfer
chamber of the substrate processing system; and one or more storage
racks associated with the load-lock chamber for receiving and
temporarily storing substrates. At least one of the one or more
storage racks may be a cooling rack, preferably including a cooling
element, adapted to cool processed substrates following processing
by the substrate processing system. Further, at least one of the
one or more storage racks may be a pre-heating rack, preferably
including a pre-heating element, adapted to pre-heat unprocessed
substrates prior to processing by the substrate processing system.
Still further, the staging module may include one or more cooling
racks, preferably including a cooling element and one or more
heating racks, preferably including a heating element.
BRIEF DESCRIPTION OF THE DRAWINGS
So that the manner in which the above recited features, advantages
and objects of the present invention are attained and can be
understood in detail, a more particular description of the
invention, briefly summarized above, may be had by reference to the
embodiments thereof which are illustrated in the appended
drawings.
It is to be noted, however, that the appended drawings illustrate
only typical embodiments of this invention and are therefore not to
be considered limiting of its scope, for the invention may admit to
other equally effective embodiments.
FIG. 1 is a top schematic view of a first embodiment of a vacuum
system in accordance with the present invention.
FIG. 2 is a perspective view of a vacuum system in accordance with
the present invention.
FIG. 3 is a partial perspective view of a vacuum system in
accordance with the present invention, showing the staging area
associated therewith.
FIG. 4 is a perspective view, showing an embodiment of a load-lock
chamber and staging rack in accordance with an embodiment of the
present invention.
FIG. 5 is a side view of an embodiment of a load-lock chamber and
associated cooling station in accordance with an embodiment of the
present invention with a portion of the side wall removed.
FIG. 6 is a perspective view of an alternative embodiment of dual
load-lock chambers and staging racks in accordance with an
embodiment of the present invention.
FIG. 6A is a perspective view of an alternative embodiment of a two
stack loadlock chamber and staging racks in accordance with an
embodiment of the present invention.
FIG. 7 is a top schematic view of a second embodiment of a vacuum
system in accordance with the present invention.
FIG. 8A is a side view of an embodiment of a single stack load-lock
chamber and associated cooling station in accordance with an
embodiment of the present invention with a portion of the side wall
removed, and also depicting a spider-type substrate support member
in accordance with the present invention.
FIG. 8B is a top view of the spider-type substrate support member
of FIG. 8A, showing the edge support studs arranged around the
periphery of a substrate.
DETAILED DESCRIPTION OF THE INVENTION
The present invention generally provides a vacuum processing system
100, which processes multiple substrates with high substrate
throughput and reduced system idle time and footprint. The system
is preferably a vacuum system having a load-lock chamber for
introducing substrates into the system and an external storage rack
associated therewith to provide pre-processing and/or
post-processing, such as heating or cooling, of substrates. The
substrates can be any size, such as 200 mm, 300 mm, or larger. The
load-lock chamber preferably includes a heating element, such as a
heating lamp or a resistive heating element, to heat substrates
therein prior to their introduction into a processing system.
FIG. 1 is a top schematic view of a vacuum processing system 100
according to the present invention having the necessary processing
utilities supported on a main frame structure 110 (shown in FIG.
2). The processing system 100 generally includes four different
regions, namely; a front end staging area 104 where substrate
cassettes 109 are supported and substrates are loaded into and
unloaded from a load-lock chamber 112, a transfer chamber 102
housing a substrate handling robot 103, a plurality of process
chambers 106 mounted on the transfer chamber 102, and a back end
108 which houses the support utilities needed for operation of the
system 100. Each load-lock chamber 112 of the front end stage area
104 is adapted to receive one or more substrates in a cassette.
A substrate handling robot, or staging robot 113, is disposed in
the staging area 104. The staging robot 113 is adapted to load a
substrate into and remove a substrate from the load-lock chamber
112 or substrate cassettes 109. Preferably, the staging robot 113
is positioned between the substrate cassette turntables 111 (shown
in FIG. 3). The substrate handling robot 103 may have a plurality
of substrate handling blades 115 for concurrently transporting a
plurality of substrates between the load-lock chamber 112 and the
plurality of process chambers 106. The handling blades 115 of the
substrate handling robot 103 are coplanar to one another. In
addition, and by way of example only, one embodiment is shown and
described herein that is adapted for use with single-substrate
handling robots. Another embodiment shown and described herein is
adapted for use with dual-substrate handling robots. A particular
embodiment may be adapted for use with either single-substrate,
dual-substrate, or any other type of substrate handling robot
consistent with the teachings herein. The system can be adapted to
accommodate various processes such as chemical vapor deposition
(CVD), physical vapor deposition (PVD) and etch processes and the
related hardware to perform these processes.
FIG. 2 is a perspective view of a vacuum processing system 100
illustrating the front end staging area 104 having a staging
platform 114 and a computer monitor 116 supported on a monitor
shelf 118 above the support shelf 120 (shown in FIG. 3) to provide
touch control to an operator. Staging racks 200 are shown mounted
on the load lock chambers 112.
FIG. 3 shows the front end staging area 104 of the system 100
having one or more substrate cassette turntables 111 rotationally
mounted through a staging platform 114 supporting one or more
substrate cassettes 109. The substrate cassettes 109 are adapted to
contain a plurality of substrates mounted in a spaced vertical
arrangement. A front end substrate handler, preferably a staging
robot 113, is disposed on the staging platform 114 adjacent to the
substrate cassette turntables 111 and a pair of load-lock chambers
112. Preferably, the staging robot 113 includes a substrate mapping
system to index the substrates in each substrate cassette 109 in
preparation for loading the substrates into a load-lock cassette
disposed in the load-lock chamber 112. One substrate handler with a
substrate mapping system used advantageously in the present system
is available from Equippe Technologies, located in Sunnyvale,
Calif., as Model Nos. ATM 105 or 107. The substrate mapping sensor
verifies the number of substrates and orientation of the substrates
in the cassette 109 before positioning the substrates in the
load-lock chamber 112 for processing or in a staging rack 200
mounted on the load-lock chamber 112. Additionally, an exhaust
system and filter 122, such as an ULPA filter, available from
Enviroco Corporation located in Albuquerque, N. Mex.; Flanders
located in San Rafael, Calif., or Filtra located in Santa Ana,
Calif., is mounted to the bottom of a support shelf 120 above the
platform 114 to provide particle control in the front end of the
system.
FIG. 4 is a substantially side perspective view of one embodiment
of a load-lock chamber 112 of the invention. The load-lock chamber
112 includes; a sidewall 202 engaging the transfer chamber 102 on
one side and the front staging area 104 on the other side, a bottom
204 positioned below the sidewall 202 and a lid 206 disposed
parallel to the bottom 204 and on which the staging rack 200 is
mounted. The load-lock chamber is preferably made of aluminum. An
access port 105 is disposed in the sidewall 202, opposite a loading
port 208, having a substrate loading door 210 mounted thereon, to
allow substrates to be transferred from the load-lock chamber 112
into the transfer chamber 102. A slit valve 107 is preferably used
to seal the access port 105 and loading port 208 when isolation or
staged vacuum is desired. A service port and service door or window
(not shown) may be disposed on one side of the load-lock chamber
112 to provide service and visual access to the load-lock chamber
112. A loading door 210 and door actuator 212 are shown in a closed
and sealed position in FIG. 4. The actuator 212 is disposed below
the loading door 210 and is in communication with the loading door
210 by movable shafts 214. The actuator 212 rotates laterally away
from the sidewall 202 to unseal the door 210 and then the movable
shafts 214 are lowered to provide clearance of the door 210 and
access to the port 208. One door actuator used to advantage is
available from VAT, located in Switzerland.
A load-lock cassette 218 is disposed within the load-lock chamber
112 to support a plurality of substrates in a spaced relationship
in the load-lock chamber 112. The load-lock cassette 218 preferably
includes two or more cassette plates 222 or other substrate
supports disposed in a spaced vertical relationship to support two
or more substrates in a stacked vertical arrangement. Preferably,
the cassette plates 222 include substrate seats 220, which are
preferably formed of a ceramic or other material suitable for
semiconductor processing. The cassette plates 222 are semicircular
in shape and are cantilever mounted to a shaft 224. The shaft 224
is disposed through the bottom 204 of the load-lock chamber 112 and
is connected to a motor (not shown), such as a stepper motor or
other elevator system. The elevator system disposed below the
load-lock chamber 112 moves the shaft 224 upwardly and downwardly
within the load-lock chamber 112 to locate the cassette plates 222
on a plane in alignment with a staging robot 113 used to load or
unload substrates from the load-lock chamber 112.
Preferably, the cassette plates 222 are made of anodized aluminum
and provide vertical substrate spacing sufficient to allow a robot
blade to safely pass between the plates to deliver or retrieve a
substrate. Each plate 222 is semi-circular or C-shaped and having a
raised outer portion forming a plurality, but preferably two
substrate seats 220 for supporting a substrate. The substrate seats
220 are adapted to be contiguous to the shape of the cassette
plate. The cassette plates 222 are adapted to define a central
opening 226 for facilitating placement or removal of the substrate
by the substrate handling robot 103 or the front end staging robot
113 in the load lock cassette 218. The substrate seats 220 are
adapted to allow passage for a substrate blade of the substrate
handling robot 103 or the front end staging robot 113. FIG. 4 shows
an embodiment of a C-shaped cassette plate 222 with two raised
substrate seats 220 defining a central opening 226. The substrate
seats 220 may have a plurality of substrate supports 221 disposed
thereon. The substrate supports 221 are preferably conical pins
having a base area for aligning and supporting a substrate thereon.
Preferably, four to six substrate supports 221 are disposed on the
cassette plates 222. However, any number of substrate supports 221
may be used to form a seat 220 on which a substrate rests. The
substrate seats 220 are preferably made of a material such as a
ceramic, quartz, aluminum or other suitable material used in
semiconductor processing. The substrates are preferably supported
about 1 to about 15 mils above the cassette plates 222.
Alternatively, the substrate seats 220 may comprise two elongate
members 221 positioned on either side of the cassette plates
222.
An exhaust port 230 is disposed through the bottom of the load-lock
chamber 112 and is connected to an on-board vacuum pump 228 via
exhaust line 232. The on-board vacuum pump 228 is disposed below
the load-lock chamber 112 to pump down the loadlock chamber 112 and
the transfer chamber 102. The pump 228 is preferably a high vacuum
turbo pump capable of providing milliTorr pressures with very low
vibration. One vacuum pump used to advantage is available from BOC
Edwards Vacuum Technology, Austin, Tex. However, other pumps such
as roughing pumps, cryogenic pumps or the like could be used alone
or in combination with one another.
Gas-bound particles are prevented from entering the transfer
chamber 102 by continually exhausting gases out of the system
through the load-lock chamber 112. A gas diffuser 231 is preferably
disposed in the sidewall 202 of the load-lock chamber 112 to
facilitate venting up to atmosphere. The gas diffuser 231 is
preferably a conduit disposed in the load-lock chamber and may be
connected to a gas purge line (not shown) such as a nitrogen purge
gas line. The gas diffuser 231 distributes the purge gas along a
larger surface area through a plurality of gas diffuser ports 233
disposed along the length of the diffuser 231, thereby decreasing
the time needed to vent the load-lock chamber 112 up to atmosphere.
It should be noted that the atmospheric volume within the load-lock
chamber 112 is desired to be as small as practical while providing
suitable volume for operation of the components contained therein,
thus providing for quick and efficient pump down and venting of the
load-lock chamber 112. It has been found that, by limiting the
volume to permit containment of only two rows of substrates within
the load load-lock chamber 112 during pump down and/or venting, the
pump down and venting time can be reduced to about 8 seconds.
An external staging, or storage rack, 200 is preferably disposed on
a load-lock chamber 112, and is coupled with an associated heat
sink 250 in accordance with an embodiment of the invention. The
staging rack 200 is shown mounted external to the transfer chamber
102 and the load-lock chamber 112, and is preferably integral with
or mounted above to the load-lock chamber 112 for easy access
thereto by the staging robot 113. It should be understood that the
staging rack 200 may also be separate from the load-lock chamber
112 and mounted at any location within the front-end staging 104
area suitable for access by the staging robot 113. It should be
further understood that the staging rack 200 may be used for
storing and cooling processed substrates after processing prior to
their replacement into a substrate cassette 109 and for staging of
the substrates prior to their transfer into the load-lock chamber
112. Accordingly, the staging rack 200 may include substrate
heating mechanisms, substrate orienting mechanisms or other
mechanisms for preparing the substrates for processing prior to
their placement within the load-lock chamber 112.
The staging rack 200 is preferably comprised of a plurality of heat
transfer plates 240 disposed in a spaced vertical relationship. The
heat transfer plates are cantilever mounted to a heat sink, or
radiator 250, which preferably includes a fluid input port 252 and
a fluid output port 254 for circulating a fluid, such as a coolant
or heating fluid, within or in fluid communication with the heat
sink 250. The heat sink 250 is in thermal communication with each
of the heat transfer plates 240, which are preferably made of
aluminum. Heat is conducted from the substrate to the heat transfer
plate 240 and then to the heat sink 250 and absorbed by the
circulating coolant. In a particular embodiment, a coolant fluid,
such as water or other coolant, is circulated through the fluid
input port 252, through the heat sink 250 and through the fluid
output port 254. A heat exchange element is preferably disposed
remote from the heat sink 250. Additional cooling or pre-cooling of
the coolant fluid may take place through conventional remote
cooling facilities (not shown) such as by conventional
refrigeration devices prior to pumping the coolant fluid throughout
the staging rack 200. Each transfer plate 240 is in thermal
communication with the heat sink and in a spaced vertical
arrangement with each other. Each heat transfer plate 240 is
preferably adapted to have a plurality of centering pins or guide
pins 242 disposed therein which can be used to assist in the
placement of a substrate on the staging rack 200. Preferably, the
guide pins 242 are tapered or conical in shape so that the
substrate can be placed within the boundary defined by the guide
pins 242 when off center but, when lowered to the surface of the
staging rack 200, the substrate is positioned properly for further
removal by the robot. Additionally, the staging rack 200 may also
include a cooling element (not shown), such as a fan or condensing
unit, to facilitate cooling processed substrates retrieved from the
load-lock chamber 112 prior to returning the substrates to the
substrate cassettes 109 by the staging robot 113.
By placing the staging rack 200 externally of the transfer chamber
102 or the load-lock chamber 112, processed substrates may be
removed from the load-lock chamber 112 for cooling in the external
staging rack 200 while additional substrates are placed in the
load-lock chamber 112 for continued processing. Any number of slots
may be provided within the staging rack 200, so that any number of
substrates may be cooled therein until the staging robot 113
removes the processed and cooled substrates from the staging rack
200 places the substrates in the substrate cassettes 109. In this
way, the cooling process is effectively removed as a time and/or
efficiency restraint or production limitation in the vacuum
processing steps of system 100.
FIG. 5 is a front view of an embodiment of a load-lock chamber 112
and associated cooling station in accordance with an embodiment of
the invention with a portion of a side wall 202 removed. In the
embodiment shown in FIG. 5, two rows of substrate seats 220 are
provided in the load-lock chamber 112 to support two substrates in
a spaced relationship. The cassette plates 222 are each supported
by the moveable shaft 224, which is disposed at least partially
through the bottom of the load-lock chamber. The edges of the
cassette plates 222 engaging the shaft 224 are supported in a
vertical spaced relationship by spacers 236, which are secured
thereto with pins 234. Each plate 222 defines a central opening 226
to form a slot for the robot blade to pass under the substrate when
the substrate is supported on the seat 220. It should be noted that
two load-lock cassettes 218 could be provided in a single load-lock
chamber 112 with either separate shafts 224 or a single integrated
shaft 224 supporting the cassette plates 222. In this embodiment,
two rows of substrate seats 220 are provided in each load-lock
chamber 112 in two separate stacks or columns to support a total of
four (4) substrates in spaced relation to allow two substrates to
be transferred along side one another.
The embodiment of FIG. 5 also includes a rapid heating module, or
heating element 260, which may be provided integrally with
load-lock chamber 112 for pre-heating unprocessed substrates prior
to their introduction into the transfer chamber 102. Preferably,
the heating element 260 is disposed below the load lock chamber 112
and in communication with the load lock chamber 112 via quartz
windows 262 disposed vertically below the load-lock chamber and
above the heating element 260. Preferably, the heating elements 260
associated with the load-lock chamber 112 are conventional
resistive heating lamps. The window is preferably made of quartz.
However, any suitable material that is substantially transparent to
thermal energy can be used. The heating element is preferably
protected from the vacuum environment of the load-lock chamber 112
or other operating environment.
Alternatively, the heat transfer plates 240 may have a resistive
heating element 244 disposed thereon or embedded therein and may be
used to selectively heat substrates disposed on heat transfer
plates 240. Because the heat transfer plates 240 are located in
ambient environment, resistive heating can be used to pre-heat
substrates prior to entry into the load-lock chamber or as a
post-processing treatment if desired. It has also been found that
pre-heating of substrates prior to processing can reduce substrate
temperature stabilization time by as much as 75% or more, thereby
greatly improving the throughput of the system. Preferably, the
heating element 244 associated with heating individual substrates
is a resistive type coil heating element.
It should be noted that any of the heating elements 260 or 244 may
be selectively activated and de-activated depending on whether the
substrate within load-lock chamber 112 has been processed and
whether it is desired to cool and/or pre-heat a particular
substrate. In the event that the substrate within the load-lock
chamber 112 has been processed, it may not be desirable to further
heat the substrate. Instead, it may be desirable to permit the
substrate to cool down prior to being placed in the staging rack
200. Accordingly, the heating element would be de-activated.
Alternatively, in the event that the substrate contained within the
load-lock chamber 112 is waiting to be processed, the heating
element 260 may be activated so that the substrate will be heated
to a desirable temperature prior to processing. In addition,
although not shown, a removable shield may be provided between the
heating element 260 and the substrate to selectively shield the
substrate from the radiant energy from the heating element 260 to
limit, prevent, or otherwise control the heating of a particular
substrate.
FIG. 6 is a substantially side perspective view of an alternative
embodiment of the invention showing a pair of load-lock chambers
112 disposed in a tandem chamber configuration 270. The load-lock
chambers 112 are similar to the embodiment described in reference
to FIGS. 4 and 5. In the embodiment shown in FIG. 6, two rows of
substrate seats 220 are provided in each load-lock chamber 112 in
two separate stacks or columns to support a total of four (4)
substrates in spaced relation to allow two substrates to be
transferred along side one another. Each tandem load-lock chamber
112 has an external staging rack 200 mounted vertically thereon.
The staging racks 200 of the tandem load-lock chambers 112 may be
cooling racks providing cooling of a substrate, pre-heating racks
providing pre-heating of a substrate, or a combination thereof.
FIG. 6A is a substantially side perspective view of an alternative
embodiment of the invention showing two load-lock cassettes 218
provided in a single load-lock chamber 112 with either separate
shafts 224 or a single integrated shaft 224 supporting the cassette
plates.
FIG. 7 shows an embodiment of the invention in which a processing
system 100 having a plurality of load-lock chambers 112 each having
a single stack of two substrates. In this an embodiment a single
load-lock chamber 112 may be provided at a plurality of facets of a
transfer chamber 102, preferably two load-lock chambers 112 mounted
at two facets and in communication with the front end staging area
104. A transfer chamber 102 is in communication with a plurality of
substrate processing chambers 106 and housing a single blade
substrate handling robot 103 wherein the substrate handling robot
103 transfers substrates to and from the substrate process chambers
106. The staging robot 113 may be mounted on a track 117 to provide
lateral travel of the staging robot 113 and access to a plurality
of load-lock chambers 112. In this embodiment, the staging, or
storage rack 200 may be mounted to or disposed integral with
load-lock chamber 112 according to the first embodiment shown in
FIGS. 5 and 6 or may be connected to or otherwise associated with
staging area 104. As shown in FIG. 7, separate staging racks 200
may be provided proximate each substrate cassette 109 for efficient
transfer of processed and unprocessed substrates. In operation, the
second embodiment operates substantially the same as that of the
first embodiment, except that the staging robot 103 would retrieve
a single substrate at a time from one of the one or more load-lock
chambers 112.
FIGS. 8A and 8B illustrate another embodiment of a substrate
support member disposed in a load-lock chamber 112. The embodiment
shown is referred to as a modified load-lock, or spider-type,
assembly 300 which may be utilized to minimally support the
substrates 302 within the load-lock chamber 112 near their edges
rather than on the substrate supports 220 described above in
reference to FIGS. 4 and 5. By minimally supporting the substrates
near their edges, the modified load-lock cassette assembly 300
minimizes thermal conduction from the substrates during and after
the pre-heating process while the substrates remain within the
load-lock chamber 112 prior to processing. In the embodiment shown
in FIGS. 8A and 8B, the spider-type assembly includes a plurality
of cassette arms 304 each having a substrate support 310 connected
thereto to support two substrates in a spaced vertical
relationship. Four substrate supports 310 are preferably provided
for each substrate 302 supported thereby. The cassette arms 304
extend radially from the central shaft 224 and are arrayed
circuitously around the substrate 302. The supports 310 define a
recess formed at the end of each cassette arm 304. The supports 310
define an annular central channel 306 forming a slot for the robot
blade to pass under the substrate when the substrate is supported
on the cassette assembly 300. The modified load-lock cassette
assembly 300 is supported axially by the moveable shaft 224, which
is disposed through the bottom portion of the load-lock chamber. It
should be noted that two load-lock cassettes 218 could be provided
in a single load-lock chamber 112. In this embodiment, two rows of
cassette assemblies 300 are provided in each load-lock chamber 112
in two separate stacks or columns to support a total of four (4)
substrates in spaced relation to allow two substrates to be
transferred along side one another. In the spider-type assembly
300, the heating element 260 can be mounted vertically above the
load-lock 112 and vertically below the storage rack 200 as shown in
FIG. 8A or below as shown in FIG. 5, to provide heating to the
load-lock 112.
The spider-type assembly 300 shown in FIG. 8 is a single stack
load-lock chamber 112. However, it should be understood that the
modified spider-type load-lock assembly 300 may also include
support structures 310 for supporting two or more stacks of
substrates. Similarly, it should be understood that any number of
support assemblies are contemplated which could be used to support
two rows of substrates in one or more stacks within the load-lock
chamber of the present invention.
In operation, processed substrates are allowed to cool in the
staging rack 200. Thereafter, the staging robot 113 retrieves the
processed and cooled substrates from the staging rack 200 and
returns the processed substrates to the substrate cassette 109. In
this way, continuous processing of the vacuum processing system 100
may be provided without requiring substrate handling robot idle
time while the load-lock chamber 112 pumps down to a vacuum level
and/or vents up to atmosphere. It should be noted that the
processed substrates may accumulate in staging, or storage rack 200
until the staging robot 113 has sufficient idle time to remove the
processed and cooled substrates from therewith for placement within
awaiting substrate cassettes 109.
It should be understood that, in a particular embodiment, the
unprocessed substrate or set of substrates may be retrieved from
within the substrate cassette by the staging robot 113 and placed
within the load-lock chamber 112 prior to retrieval of the
processed substrate or set of substrates from within the load-lock
chamber 112 and placement of the processed substrate or set of
substrates within the staging or storage rack 200 by the staging
robot 113, in which the substrates may be cooled as previously
described.
In addition, a substrate can be heated prior to entry into the
loading lock chamber 112. Pre-heating of the substrate may occur by
activating the resistive heating element 244 disposed on or in the
heat transfer plates 240 prior to being transferred to a load-lock
chamber 112. In such an embodiment, the staging robot 113 retrieves
an unprocessed substrate from a substrate cassette 109 and
positions the unprocessed substrate on an empty heat transfer plate
for heating. Thereafter, the heating element 244 associated with
the staging rack 200 is activated to pre-heat the substrate.
Following pre-heating, the staging robot 113 retrieves the
pre-heated substrate and places the pre-heated substrate in the
load-lock chamber 112 for further processing.
While the foregoing is directed to preferred embodiments of the
present invention, other and further embodiments of the invention
may be devised without departing from the basic scope thereof. The
scope of the invention is determined by the claims which
follow.
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